How Detect Differentiation Between SUS 304 and SUS 201?

we are a trade company which work on Sink and Gas and Hood. when we go to some factory at China, they told us that manufacture made from SUS 201 , but we want change that to the SUS304,they told they will do it, but we do not know how we can understand differeantiation between SUS 201 & SUS 304, as we know via Magnet possible but we want understand other easy and usefull method which we use at factory to test the different between this and that? and if is it possible give me some teachnical information about SUS 304 and SUS 201. as i know this materal have diferentiation about Ni Cu Co etc but i need sum up this information and what element improtant in SUS 304 and what element important about 201. i should pay attention to which part of element of this?